Processing carbonaceous solids



May 6, 1952 w. w. ODELL ET AL PROCESSING CARBONACEOUS SOLIDS 2 SHEETS- SHEET i Filed June 14, 1947 m, N 1\ l QQSQL N1 @NBN S fr y d E m ,2W Wm @w l ww m my m i .0. .rev w L 1: wx n i ,y um, v-\,\ mw wwf e U u j A m ml.: J.: ,m |)kwmmuxm w v Si E 1 A||I N Si( N ENQ www m. x www Patented May 6, 1952 PROCESSING CARBONACEUS SOLIDS William W. Odell, Washington, D. CL, and George L. Matheson, Union N. J., assignors'lto Standard Oil Development Company,. a corporation of Delaware Application June' 14, 1947, Serial No. 754,624

(Cl. NZH-31)" 12 Claims.

This invention relates to a process of producing coke orchar of low sulfur content, from coal, lignite and other carbonaceous solids of relatively high sulfur content. In particular it has`v to do with the treatment of coal initially in a nely divided state whereby the ash content is'V materially reduced, the carbonization of the coal at an elevated temperature, and elimination of. the remainingv sulfur compounds by subjectingY the hot freshly carbonizedv coal in a nev state of sub'- division to the reducing action of a reducing gas such'. as hydrogen.

When coal is carbonized in a fine state'of sub'- division, such as occurs when powdered coal is continuously introduced into afluidized` mass of incandescent carbonaceous solids which solids may be previously carbonized coal, the resulting product can be treated,.as defined hereinafter, by treatment with a reducing gaseousruid ata temperature of the order of 400 to 600 C.,` and the sulfur content of thev carbonized product de'- creased by virtue of contact of the reducing gases with the freshly carbonized nely divided product. It has long been known that reducing gases when passed over hot coke will tend to reduce `they sulfur'content of the coke but no practical ap-` plication of this hasbeen possible, so` far as Wev are aware, for a number of reasons. First coking processes have not' been developed whereby coking coal could be carbonized in a fine stateofV division without forming. lump coke. Again lump cokes does not readily lend itself to the desulfurizing process by treatment with hydrogen.

Another difficulty in the practical application of known procedures, so far as we are'aware, is that of eliminating sulfur' present initiallyv in the coal as gypsum. The gypsum athightemperatures of the order of 1300 to 1500* C'. is dissociated but at the temperatures common to carbonation dissociation does not occur but rather a partial reduction occurswhereby a calciumsulphide, chiefly'the monosul'phide, form'sfand the elimination of this sulfur is a lengthy procedure unless the char or coke under process is' very nely divided.

The present invention deals with improvements andcombinations whereby the sulfurinitially present in various forms in coal can be very largelyy eliminated in a relatively short period of time yielding a carbonizedl product in. a nely divided state with a very low sulfur content.

One ofthe objects of this invention is to pro duce a solid highly carbonaceousvnely dividedfuel which has-so low a sulfur lcontent that it is a preferred fuel for use in metallurgical and gas-1 Y Z makingprocesses. Another object is to produce a carbonized s'olidfuel of low sulfur content which. can Ibe utilized in the manufacture of briquettes for domestic or other uses. Still another objectistor produce an active carbon of low" sulfur content which may be used with or combi-nedV with? catalysts usable in promoting chemicall reactions. Other' objects will appear fr'orn the disclosures made hereinafter.

W'el'iavedescribed in Serial No. '726,530 filed inl theA- U. Sl- Patent Ofce February 5, 1947, a process.I by whichA coalV can be largely de-ashedv and' appreciable portions ofv the gypsum and pyrite' when they are present with the coal can be el-in'iinatle'd therefromby fluidizing the coal in a finely-C dividedY state under denitely prescribed conditions. We have alsol described in Serial No.r 754,623 filed in the U. S. Patent Office June 14; 1947,*and now abandoned' a process in which the treated (partly de-ashed) coal is carbonized rapidlyf at high temperature by introducing it in a fnestateof division intoahot uidized mass of nely divided coke to produce a char which has a verylarge'surfacearea per unit of weight.

According to our' present invention coal, thus treated (de-ashe'd-)- and quickly carbonized, is subsequently treated with a stream of hot reducinggas such a'sone comprising hydrogen or hy'- drog'en in admixture with carbon monoxideV at a temperature of the order of 400 to 600v C., whereby the sulfur content of 'the quickly'car'- bonize'dl product isl not onlyV materially reduced butitfis'- reducedso rapidly that the process is' commerciallyv feasible. Although we do not limit above 900 Fiian'dbelow about 2000" F., and pref#- erablyv conducting carbonizationin the presence of some steam and/or subsequently steamingthe carbonized product for a brief period, the basic or specic feature with which this inventionis particularly concerned is thetreatment of the carbonizedV product thus prepared while still hot and while at a temperature or" the order of .400- to 600 C. with a reducing gas such as or includinghydrogen fora period suicientto materially reduce the sulfur content of the carbonizedproduct'. Best results are obtained when ourselves to the treatment of a freshly carbone the carbonized product treated with a reducing gas has been freshly prepared as described.

The operation will be better understood with reference to the accompanying drawing, in which;

Figure 1 shows diagrammatically in elevation but largely as a flow diagram one type of apparatus in which the process of this invention may be practiced, adapted for the treatment of previously carbonized finely divided solid fuel at the aforementioned temperatures with a reducing gas; and

Figure 2 shows in a similar diagrammatic manner another embodiment of the invention particularly suited for operation at temperatures above about 1650 F., depicting especially a reactor with a double packed portion.

Referring to Figure 1, reservoir I is adapted to receive hot, freshly carbonized, highly carbonaceous finely divided solids from a carbonizer through valve 2. It functions as a stripper for gases associated with the solids, the gases passing out through valve 3. The hot carbonized solids pass down under control through valve 4 into reactor 5 wherein they are fluidized by means of gas which may pass chiefly through valves 6 and 1 into the reactor through grid 8. Gasiform uid also may pass into 5 through valve 28 and conduit 9, and also through valve I4. The reactor has a packed zone I2 located in a middle zone thereof. This packed zone contains large size bodies as shown in similar packed zones in Figure 2. The bed of fluidized solids extends above and below I2 into zones B and A respectively, the top level of the bed being at L. The gas stream from the reactor passes out hot through offtake I5, valve I6, heat exchanger I1, sulfur removal apparatus I8 and offtake I9 from which a portion is bled through valve 25 and a portion passes on through 2D, valve 2|, pump 22, exchanger I1 and'conduit 23 back tothe reactor. For cooling purposes gas may be returned to the reactor through bypass conduit 21 and valve 28. The sulfur removal may be effected in any known manner asby contacting the sulfur containing gas withva sulf-reactive metal or the like.

Fresh reducing gas may be supplied to the system through valve l. Combustion supporting gas may be introduced into the reactor through valve 29, and bustle pipe 30. Thermocouples are shown at 32 and 33.

In Figure 2 the same system of numbering is employed except that the packed portions of the reactor 5 are numbered I2A and I2B, and the free zone wherein finely divided solids may be in free fluidized motion are lettered A, B, and C.

Irrespective of the packed zones, I2 of Figure 1 and I2-A and I2-B of Figure 2, it will be understood that the fluidized bed of solids is continuous from top level L to the bottom zone A, the bed density in the packed zone being less than in the non-packed zones. The packing is supported on supporting grids which are pervious to the flow of gas therethrough and in which the finely divided solids are substantially in a fluidized state.

Example 1 Referring to Figure 1 and considering the treatment of a carbonized de-ashed coal made by quickly heat treating f-lnely divided coal in a fluidized bed of finely divided coke at a temperature above 900 F. and below 2200 F. preferably at 1050 to 1650 F. the operation may be conducted as follows: Pass the hot, freshly carbonized f tain the char in 5 in a uidized state. The gas from 6 and I passes up as a stream through porous member 8 into the bed of char. The gas introduced through 6 is a reducing gas preferably substantially free of H28 and at a temperature above F. and preferably above 600 F. but -below that temperature at which damage to equipment might occur. The treated char is removed from the reactor through conduit 9 and valve I0, preferably continuously at a rate adjusted to suit the desired reduction in the sulfur content of the char; the rate being synchronized with the feed rates so that the levels L and LA are maintained.

The gas stream passing up through grid 8 and flaring member Il passes serially through a free 'zone A, the packed portion I2 and free zone B and then through dust separator I3, offtake I5, valve I6, heat exchanger I1 wherein its tempera- .ture is reduced, sulfur removal vessel I8, conduits I9 and 20, valve 2|, pump 22 and back through exchanger I1 wherein its temperature is raised, through conduit 23 and valve 6- and is again circulated through reactor 5. Excess gas is bled from the system through valve 25; additional fresh reducing gas as may be required is introduced through valve 1. The by-pass conduit 21 with valve 28 is Vused to reduce the temperature of the outgoing treated char by allowing cooled gas to pass up through conduit 9 and through Ythe char in aring member I I.

Sulfur exists in lignite, coal, coke, char and certain other carbona-ceous solids in a number of different forms which should be considered in treating them at elevated temperatures. For example the sulfur present as free sulfur, held in solid solution, upon reacting with hydrogen generates a small amount of heat; that is, the reaction is exothermic substantially as follows:

This reaction is not favored by extremely high temperatures; a temperature approximately or somewhat above the boiling point of sulfur is preferred. Similarly ferrous sulfide is reduced by reaction with hydrogen with the evolution of heat as in Equation 2.

At higher temperatures the endothermic reaction expressed by Equation 3 occurs (3) FeS+H2O=FO+H2S-17.6 Calories Although water vapor is not usually considered a reducing gas, it may advantageously be employed with reducing gas as a fluid for treating hot carbonaceous solids in a fine state of subdivision at high temperatures, namely above about l500 F. Under these conditions the reaction for the removal ofsulfur is more complex than indicated by Equation 3. For example carbon reacts with steam at high temperatures forming carbon monoxide and hydrogen, also by endothermic reactions; the carbon monoxide, hy-

drogen and carbon are reducing agents tending. to. reduce iron sulfide and oxides to iron simultaneously forming volatile sulfur compounds.

The heat recovered in the heat exchanger II of Figure 1 is usually sufficient to. carry on the operation, when the char supplied throughvalve 2 is. at a high. temperature; However, when considerablesulfur is. to be removed or when the temperature 'of the char thus fed to the reactor. 5 is not at a suci'ently high temperature. to. main.- tain the desired temperature in the bed of charin process the extra. heat: may be. suppliedby introducing a relatively small amount. of air or other combustion supporting gasv as. through valve 29, bustle-pipe 3.6)` and inlets 3 I.

Summarily the operation comprises passing a stream initially comprising essentially a reducing gas at an elevated temperature upwardly through a bed of finely divided solid char, preferably fluidized, while said' char is at an elevated temperature suitable for the chemical reaction of sulfur contained therein, continuously feeding fresh hot char to an upper portion of the bed and continuously withdrawing the treated char from a zone of said bed adjacent the bottom thereof, meanwhile, introducing a relatively small amount of steam and/cr air into a zone of said bed adjacent the bottom thereof, as required; the total amounts. of air and steam used preferably should be kept to such low limits that the gas stream as dis-charged through oiftake I5 of Figure 1 is still a reducing gas.

Under some conditions the gas discharged from stripper I through 3 of Figure 1 is a. reducing gas and this, under these conditions, may be circulated. as a reducing gas using valve `I as a control. However, it. will be noted that in applying the foregoing disclosure the reducing gas circulated through the systemY may be generated in amounts required bythe use4 ofthe small amounts of. steam and combustion supporting gas4 described when the temperature in the. fiuidized bedof char in reactor 5 is maintained at a temperatureabove about 1600 F. and preferably in thev range 1650.o to1750 F. Higher temperatures may be employed but commonly employed alloy steels are. not so satisfactory as. materialsfof` construction of certain exposed equipment at these temperatures.

Referring to Figure 2 the operation is substantially as described. but additional economies are obtainable. By introducingY a. combustion supporting fluid in zone C separated from zones A and B by packed zones I 2A and IZB respectively it'is'possible to maintain a high temperature in zone C and a lower temperature in zones A and B. Zone Bis cooler because of the endothermic water gas reaction in. the bed and also because fresh feed is or may be supplied ata lower temperature through feed valve 4. A may be appreciably cooler by virtue of cooling fluid introduced therein through Valve 28;- and/ or valve I4. Similarly a coo-ling gasiform. medium may be introduced through valve 'I. In this manner the treated char not only contacts the reducing gas after passingA through the hottest zone or combustion zone C but some. of the sensible heat initially in the char as it leaves zone C is returned thereto in thev upwardly moving stream of reducing gases from zone A. Thisv not only permits a heat economy to be made but it. minimizes the amount of combustion supporting fluid which may be required in zone. C.

In carrying out the' desulfurization operation as described thereis a. relationship between the Zone the approximate velocities of the gas stream leaving the bed, for satisfactory conditions, should be about 0.35.and 2.5 feet per second respectively; velocity calculated as for a gas stream in. an empty reactor at standard conditions of temperature and pressure. The ner the size of char particlesl treated the more readily or more quickly is the sulfur contentl reduced. Whereasl the size of char used dependsA upon the ultimate use to which the treated product is put, it is preferable, other factors remaining the same, to treat char having a mean particle size less than one-eighth (1/8) inch. The sulfur content of the treated product, without using excessive or uneconomical amounts of reducing gas, may be as low as 0.1 percent or even lower according to size of char treated, the initial sulfur content of the feed char, and the duration of the treating period.

In the foregoing consideration has been given primarily to the removal of sulfur and its compounds from carbonized carbonaceous solids (char). l It is not always desirable to precarbonize before treating. In other words nely divided carbonaceous solids such as oxidized coal, animal, bones, and certain other materials may be treatedv asdescribed by feeding them into the reactor without precarbonization. Bone is treated to make a carbonaceous absorbent rather than to desulfurize.

The residence time of the carbonaceous solids within the reactor in counter contact with hot gases is usually more than one minute and the total depth of the uidized -bed is preferably more than 10 feet and may advantageously be more than 20 feet particularly as the diameter increases from about 5 feet. With the iiuidized solids descending through the reactor at a mean velocity of 5 feet per minute, the duration of residence time of the carbonaceous solids in the reactor, .when the bed is 20 feet deep, is 4 minutes. Employing the latter residence time and using a gas velocity of say 1 foot per second the approximate volume o'fgas passed per square foot of mean sectional area of the reactor during the 4 minutes is 240 cubic feet. The approximate quantity of carbonaceous solids treated with this 240 cubic feet of gas in 4 minutes is say 300 pounds. In order to increase the volume of gas used per unit weight of carbonaceous solids treated one can decrease the rate of discharging the treated char which increases residence time inthe reactor, or within certain limits, increase the gas velocity, or both. It will be noted that the bed density in the reactor as shown in the Figures at 5 is less in the packed portion (or portions) `than in the remainder of the bed.

Organic sulfur reacts with steam yielding hydrogen sulde and carbon dioxide commonly by reactions which are endothermic and .these reactions are` favored by high temperatures. the

overall reactions wherein the carbon dioxide formed reacts with incandescent carbon to form carbon monoxide absorb a greater amount of heat than the straight sulfur reactions. Sulfur combinesjwithrcarbon monoxide to form carbonyl 7 sulflde and this reaction is exothermic but occur at an elevated temperature. The total amount of heat energy due to the oxidation or removal of sulfur from the char is very small, but elevated temperatures are required for promoting the desulfurizing reactions. It will become evident that, with good heat exchange in exchanger I1 of the figures, only a small amount of heat energy need be supplied to the system and this canibe accomplished by introducing the combustion supporting iiuid as through 29 and 30 as described. By removing the treated char from the reaction chamber at a lower temperature than that at which it is fed into the reactor makes possible the further economy of heat.

Before defining my claims attention is called to the fact that the operation described can be conducted at reduced pressure, normal, or at superatmospheric pressure. It is usually economical to operate at pressures not appreciably greater than atmospheric. The duration of time the solids in process are resident in the reactor is determined by the result sought. Samples of the treated material as discharged through 9 andi() of the figures are analyzed and if they signify undertreatment the residence time is increased by decreasing the rate of discharge of solid through 9 and l0 and, when desired, the rate of circulation of reducing gas is increased. The circulation rate can only be varied within limits determined by the quantity of blown over solids and by the desirability to maintain the solids in a iiuidized state in the reactor.

Oxidation, conducted at a temperature below 600 C. or about 500 to 550 C. with oxygen is conducive to the removal of sulfur from such products as high temperature coke and this is particularly true of cokes containing only small amounts of sulfate sulfur and a larger amount of other forms of sulfur. This preferential oxidation of sulfur instead of the carbon of the coke is possible because the ignition temperature of the coke is above 550 C. We find that many carbonaceous solid fuels that contain sulfur compounds, such as low temperature coke, ignite at temperatures below 550 C. and hence preferential oxidation of sulfur is not possible at the latter temperature. Frequently its oxidation with combustion of some carbon is not economical.

It is economical to promote some oxidation reactions, as described above, wherein the heat generated is utilized in maintaining the system vat the chosen temperature, wherein the overall result of reaction is the production of a reducing gas, and wherein the carbonaceous solids thus treated are finally subjected to a strongly reducing atmosphere before they are finally discharged from the reactor in which they are treated. We nd that oxidation of sulfur in solid fuels by blasting with air occurs with most fuels, simultaneous with oxidation of carbon and the difficulty heretofore experienced has been that the accompanying oxidation of carbon generates so much heat that difficulties are experienced. Itis necessary, to obtain optimum results, to maintain a quite uniform temperature throughout the mass of solids being treated, in the oxidation zone, or rather in the zone in which combustion supporting gas is introduced. This cannot be accomplished in a xed bed but is readily accomplished in the manner described above.

The foregoing description and examples of operations have been presented to show specific applications of this invention and some of the results attainable by its use. Other modifications 8 will be obvious to those skilled in the art hence only such limitations should be imposed on the invention as are indicated in the following claims.

We claim:

1. The process of beneciating carbonaceous solids in the form of finely divided de-ashed and carbonized coal comprising passing a mass of said solids substantially continuously downwardly in a fluidized state through a stationary porous mass of substantially uniformly sized, relatively largesize heat-resistant solids confined in a reaction chamber, while passing a stream of hot, initially strongly reducing gas upwardly therethrough in counter current contact with the said carbonaceous solids, introducing into the gas stream during its contact with said carbonaceous solids in said reactor a relatively small amount of a combustion supporting gas and promoting combustion reactions in said stream in contact with the latter solids, controlling the supply of said combustionsupporting gas so as to generate the heat in the reactor while maintaining the resulting reacting gas reducing, discharging the resulting reducing gas stream overhead, substantially continuously discharging the thus treated carbonaceous solids from beneath the mass of said large-size solids While continuouslyfeeding fresh de-a'shed andcarbonized coal to be treated to the reactor above the latter mass, synchronizing the feed and discharge of said carbonaceous solids so that a continuous deep bed of the latter solids is maintained in said reactor, said bed extending over the entire crosssectional area of said chamber from an upper point substantially above said bed through said bed to a lower point substantially below said bed, and maintaining the latter bed in a fluidized state over its entire height by controlling the velocity of the gaseous stream passing therethrough.

2. The process of beneciating carbonaceous solids in the form of nely divided de-ashed and carbonized coal comprising passing a mass of said solids substantially continuously downwardly in a fluidized state through a stationary porous mass of substantially uniformly sized, relatively largesize heat-resistant solids confined in a reaction chamber, while passing a stream of hot initially strongly reducing gas upwardly therethrough in counter current contact with the said carbonaceous solids, maintaining the latter solids while in said chamber as a deep continuous fluidized bed, introducing into the gas stream at a zone between the top and bottom of said bed a combustion supporting gas promoting combustion therein suflicient to maintain the solids while in said zone at a temperature above about 500 C. but below about 1l00 C., and insuilicient to destroy the reducing character of the resulting gas stream, discharging the resulting gaseous stream overhead and withdrawing the thus treated carbonaceous solids adjacent the bottom of said bed, meanwhile feeding fresh de-ashed and carbonized coal to be treated substantially continuously to a top portion of said bed.

3. The process of desulfurizing a solid fuel in the form of nely divided de-ashed and carbonized coal containing sulfur comprising passing a mass of said finely divided hot solid fuel substantially continuously downwardly in a lluidized state through a stationary, porous mass of substantially uniformly sized relatively large-size heat-resistant solids confined in a reaction chamber while passing a stream of hot initially strongly-reducing gas upwardly therethrough in counter current contact with said fuel, discharging the resulting gaseous stream overhead, maintaining said fuel while in said chamber in a deep continuous iuidized bed extending over the entire cross-sectional area of said chamber from an upper point substantially above said mass to a lower point substantially below said mass, and discharging the thus treated fuel from adjacent the bottom of said bed at such a controlled rate that the continuity of said fluidized bed between said points is maintained and the residence time of said fuel in said chamber in contact with said reducing gas is sufficient to lower the sulfur content of said fuel.

4. The process defined in claim 3 in which the hot fuel is supplied to the reaction chamber at a temperature above 200 C. but below about 1100 C.

5. The process defined in claim 3 in which the hot reducing gas is introduced into the reaction chamber at a temperature of the order of 100 to 500 C.

' 6. 'I'he process defined in claim 3 in which the hot fuel is fed to the reaction chamber at a temperature of the order of 400 to 1000 C. and the hot gas is supplied to the said chamber at a temperature of the order of 100 to 300 C.

7. The process defined in claim 3 in which some of the gas discharged overhead is returned to the reaction chamber as at least a part of the stream of strongly reducing gas.

8. The process defined in claim 3 in which the coal treated has been previously subjected to dry treatment for the removal therefrom of pyritic sulfur and gypsum.

9. The process of beneiiciating finely divided de-ashed and carbonized coal, comprising passing a mass of said carbonized coal substantially continously downwardly in a fluidized state through a stationary porous bed of heat-resisting largesize solids confined in a rea-ctor and occupying a portion only of the height of said reactor while passing a stream of hot reducing gas upwardly therethrough in countercurrent contact with said carbonized coal, maintaining the latter solids in said luidized state in said reactor at temperatures above 400 C. but below about 1100 C., discharging the gas stream overhead, maintaining said mass in said reactor as a deep continuous fluidized mass extending over the entire crosssectional area of the reactor from an upper point substantially above said bed, through said bed to a lower point substantially below said bed, the apparent density of said fluidized mass being lower within said bed than in reactor portions above and below said bed, substantially continuously withdrawing 'the thus treated carbonized coal from adjacent the bottom of said iiuidized mass, substantially continuously feeding fresh carbonized and de-ashed coal to be treated to a portion of the latter mass adjacent the top thereof at a rate adapted to maintain the depth of said uidized mass inv said reactor substantially uniform, and controlling the rates of solids charge and withdrawal so as to maintain the continuity of said fluidized mass between said upper and lower points.

10. The process of beneiciating carbonaceous solids in the form of finely divided de-ashed and carbonized coal, comprising passing a mass of said carbonized coal substantially continuously downwardly in a fluidized state through two stationary porous beds of heat-resistant large-size solids confined in superimposed spaced relationship within a reactor, passing a stream of hot reducing gas upwardly through said reactor in countercurrent contact with said carbonaceous solids, maintaining the latter solids in said iiuidized state in said reactor at temperatures above 400 C. but below about 1100 C., discharging the gas stream overhead, maintaining said mass in said reactor as a deep continuous fiuidized mass extending over the entire cross-sectional area of said reactor from an upper point substantially above the upper one of said beds, through said beds and the space between said beds to a lower point substantially below the lower one of said beds, the apparent density of said fluidized mass being lower within said beds than in reactor portions above said upper bed, between said beds and below said lower bed, substantially continuously withdrawing the thus treated carbonaceous solids from the bottom of said fluidized mass, substantially continuously feeding fresh carbonized and de-ashed coal to be treated to a top portion of said mass at a rate to maintain the depth of said mass substantially uniform, and controlling the rates of solids charge and withdrawal so as to maintain the continuity of said fluidized mass between said upper and lower points.

11. The process of claim 10 in which a combustion-supporting gas is supplied to said space between said beds at a rate adequate to generate heat by combustion but insufficient to destroy the reducing character of said gas.

12. The process of claim 11 in which the temperature of said uidized mass within said space is higher than the temperature of said fluidized mass above said upper bed and below said lower bed.

WILLIAM W. ODELL. GEORGE L. MATHESON.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,632,845 Oberle June 21, 1927 1,955,025 Sabel et al Apr. 17, 1934 1,983,943 Odell Dec. 11, 1934 1,984,380 Odell Dec. 14, 1934 2,327,175 Conn Aug. 17, 1943 2,358,359 Stuart Sept. 19, 1944 2,394,814 Snuggs Feb. 12, 1946 2,436,225 Ogorzaly et al Feb. 17, 1948 2,438,029 Atwell Mar. 16, 1948 2,445,327 Keith July 20, 1948 2,444,990 I-Iemminger July 13, 1948 2,473,129 Atwell June 14, 1949 FOREIGN PATENTS Number Country Date 453,072 Great Britain Sept. 4, 1936 OTHER REFERENCES U. S. Bureau of Mines R. I. `3711 May 1943 202-25 (pages 22 to 26).

Snow, Industrial and Engineering Chemistry, vol. 24 (1932), No. 8 (pages 903 to 909). 

1. THE PROCESS OF BENEFICIATING CARBONACEOUS SOLIDS IN THE FORM OF FINELY DIVIDED DE-ASHED AND CARBONIZED COAL COMPRISING PASSING A MASS OF SAID SOLIDS SUBSTANTIALLY CONTINUOUSLY DOWNWARDLY IN A FLUIDIZED STATE THROUGH A STATIONARY POROUS MASS OF SUBSTANTIALLY UNIFORMLY SIZED, RELATIVELY LARGESIZE HEAT-RESISTANT SOLIDS CONFINED IN A REACTION CHAMBER, WHILE PASSING A STREAM OF HOT, INITIALLY STRONGLY REDUCING GAS UPWARDLY THERETHROUGH IN COUNTER CURRENT CONTACT WITH THE SAID CARBONACEOUS SOLIDS, INTRODUCING INTO THE GAS STREAM DURING ITS CONTACT WITH SAID CARBONACEOUS SOLIDS IN SAID REACTOR A RELATIVELY SMALL AMOUNT OF A COMBUSTION SUPPORTING GAS AND PROMOTING COMBUSTION REACTIONS IN SAID STREAM IN CONTACT WITH THE LATTER SOLIDS, CONTROLLING THE SUPPLY OF SAID COMBUSTIONSUPPORTING GAS SO AS TO GENERATE THE HEAT IN THE REACTOR WHILE MAINTAINING THE RESULTING REACTING GAS REDUCING, DISCHARGING THE RESULTING REDUCING GAS STREAM OVERHEAD, SUBSTANTIALLY CONTINUOUSLY DISCHARGING THE THUS TREATED CARBONACEOUS SOLIDS FROM BENEATH THE MASS OF SAID LARGE-SIZE SOLIDS WHILE CONTINUOUSLY FEEDING FRESH DE-ASHED AND CARBONIZED COAL TO BE TREATED TO THE REACTOR ABOVE THE LATTER MASS, SYNCHRONIZING THE FEED AND DISCHARGE OF SAID CARBONACEOUS SOLIDS SO THAT A CONTINUOUS DEEP BED OF THE LATTER SOLIDS IS MAINTAINED IN SAID REACTOR, SAID BED EXTENDING OVER THE ENTIRE CROSSSECTIONAL AREA OF SAID CHAMBER FROM AN UPPER POINT SUBSTANTIALLY ABOVE SAID BED THROUGH SAID BED TO A LOWER POINT SUBSTANTIALLY BELOW SAID BED, AND MAINTAINING THE LATTER BED IN A FLUIDIZED STATE OVER ITS ENTIRE HEIGHT BY CONTROLLING THE VELOCITY OF THE GASEOUS STREAM PASSING THERETHROUGH. 